The Bell UH-1N Twin Huey is a medium military helicopter. A member of the extensive Huey family, it first flew in 1969. The CUH-1N Twin Huey (later CH-135 Twin Huey) was the original version, first ordered by the Canadian Forces.
The UH-1N has a 15-seat configuration, with one pilot and 14 passengers. In cargo configuration, it has an internal capacity of 220 ft³ (6.23 m³). An external load up to 5,000 lb (2,268 kg) can be carried. The UH-1N was later developed into the civilian Bell 212.
Based on the stretched-fuselage Bell 205, the Bell 212 was originally developed for the Canadian Forces (CF) under the designation CUH-1N Twin Huey. Later, the CF adopted a new designation system and the aircraft was redesignated CH-135 Twin Huey. The CF approved the development of the aircraft on 1 May 1968 and purchased 50 aircraft, with deliveries commencing in May 1971.
The US military came very close to not procuring the Twin Huey. The purchase of the aircraft for US military use was opposed by the chairman of the House Armed Services Committee at the time, L. Mendel Rivers. Rivers took this position because the aircraft powerplant, the Pratt & Whitney Canada PT6T was produced in Canada. The Liberal Canadian government of the time had not supported US involvement in Vietnam and had opposed US policies in Southeast Asia, as well as accepting US draft dodgers. Rivers was also concerned that procurement of the engines would result in a trade deficit situation with Canada. Congress only approved the purchase when it was assured that a US source would be found for the PT6T/T400 engines. As a result, the United States military services ordered 294 Bell 212s under the designation UH-1N, with deliveries commencing in 1970.
Unlike in the CF, in US service, the UH-1N retained the official name “Iroquois” from the single–engined UH-1 variants, although US service personnel refer to the aircraft as a “Huey” or “Twin Huey”.
The Bell 412 is a further development of the Bell 212, the major difference being the composite, four-blade main rotor. The UH-1N has also been developed into the upgraded, four-blade UH-1Y.
The UH-1N’s main rotor is powered by a PT6T-3/T400 Turbo Twin Pac made up of two Pratt & Whitney Canada PT6 power sections that drive a single output shaft. They are capable of producing up to 1,342 kW (1,800 shp). Should one power section fail, the remaining section can deliver 671 kW (900 shp) for 30 minutes or 571 kW (765 shp), enabling the UH-1N to maintain cruise performance at maximum weight.
The United States Marine Corps (USMC) modified a large number of their UH-1Ns with a stability control augmentation system, which provides servo inputs to the rotor head to help stabilize the aircraft during flight. This modification removed the gyroscopic “stabilization bar” on top of the main rotor head, instead relying on the computer system for stability.
- CUH-1N Twin Huey: Original Canadian Armed Forces designation for the UH-1N utility transport helicopter.
- CH-135 Twin Huey: Canadian version of the UH-1N. Canada purchased 50 CH-135s with deliveries starting in 1971. The aircraft were retired from the Canadian Forces starting in 1996 and struck off strength in December 1999. 41 of the surviving CH-135s were acquired by the US government in December 1999 and transferred to the National Army of Colombia and Colombian National Police. At least one CH-135 was destroyed in combat. 135135 was transferred to the Colombian National Police and flown by the Dirección Antinarcóticos (DIRAN). It was destroyed on the ground by FARC rebels on 18 January 2002, following an incident in which it was forced down by gunfire. Two CH-135s are on display in museums, one at the Canada Aviation Museum in Ottawa and one at the National Air Force Museum of Canada at CFB Trenton.
- UH-1N Iroquois: Initial production model, used by the USAF, USN, and USMC. Over the years, the primary operators, the USMC has developed a number of upgrades for the aircraft including improved avionics, defenses, and a FLIR turret. The USAF planned to replace their UH-1Ns with the Common Vertical Lift Support Platform to support the service’s ICBM activities, but also examined a life extension for their current fleet.
- VH-1N: VIP transport configuration
- HH-1N: SAR variant.
- UH-1Y Venom: A UH-1N replacement and upgrade as part of the H-1 upgrade program for the USMC, designed to coincide with a similar upgrade for the AH-1W attack helicopter to AH-1Z Viper standard, with common engines and other major systems.
- Agusta-Bell AB 212: Civil or military utility transport version. Built under license in Italy by Agusta.
- Agusta-Bell AB 212EW: Electronic warfare version for Turkey.
- Agusta-Bell AB 212ASW: Anti-submarine warfare, anti-shipping version of the AB 212 helicopter, built under license in Italy by Agusta. Operated by the Italian Navy, Hellenic Navy and Islamic Republic of Iran Navy, Peru, Spain, Turkey, and Venezuela.
The AB 212ASW is a Model 212 Twin Huey with a prominent radome above the cockpit. Early production had a dome-shaped radome, while later production had a flatter “drum” radome. A left side winch is used for dipping the Bendix ASQ-18 sonar. Other changes include structural reinforcement for a gross weight of 11,197 lbs (5080 kg), ECM, shipboard deck tie-down attachments and corrosion protection. Armament is two Mk 44 or Mk 46 torpedoes or two depth charges in the ASW role and four AS.12 air-to-surface wire-guided missiles for the anti-shipping role.
|Crew||4 (pilot, co-pilot, crew chief, gunner)|
|Capacity||6-8 combat-equipped troops, or 4,400 lb (1,996 kg) equivalent cargo|
|Length (rotors running)
||57 ft 8 in (17.58 m)|
|Height||14 ft 5 in (4.39 m)|
|Main rotor diameter||48 ft 0 in (14.63 m)|
|Empty weight||6529.4 lb (2961.7 kg)|
|Max take off weight||11,200 lb (5,080 kg)|
|Maximum speed (Vne)||120 knots (138 mph, 223 km/h)|
|Cruising speed at sea level||100 knots (115 mph, 186 km/h)|
|Ascent speed at sea level||1,745 ft/min (532 m/min)|
|Ceiling in service||17,400 ft (5,305 m)|
|Passable distance at sea level with standard reserve||237 nm (439 km)|
|Powerplant||1 × Pratt & Whitney Canada T400-CP-400 coupled turboshaft engine, 1,250 shp (930 kW) 900 shp (671 kW) emergency rating for each power section|
|Armament||2 external stations for 70 mm (2.75 in) Hydra 70 or APKWS II rockets
2 pintle mounts for 7.62×51 mm M240D machine guns, .50 in (12.7 mm) GAU-21 machine guns, or 7.62×51 mm NATO GAU-17/A Gatling guns